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19 terms

ch 15 vocab

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Asteroid
Also called minor planet. Astronomy. any of the thousands of small bodies of from 480 miles (775 km) to less than one mile (1.6 km) in diameter that revolve about the sun in orbits lying mostly between those of Mars and Jupiter.
Asteroid belt
The region of the solar system that is between the orbits of Mars and Jupiter and in which most asteroids orbit
Astronomical unit
A measurement equal to the distance between the Earth and the sun, a distance of about 150 million km or 93 million miles
Coma
Outer layer of a comet composed of escaping gas and dust producing a highly reflective halo
Comet
a small mass of dust and ice that orbits the sun in a long, oval-shaped path
Dwarf planet
in orbit around the sun, has sufficient mass for its self-gravity to form nearly round shape, has not cleared the neighborhood around its orbit and is not a satellite (Pluto, Eris, Ceres)
Geocentric
a former theory that the earth was at the center of the universe
Impact crater
a crater on the surface of a planet or moon produced by the impact of an asteroid, meteoroid, or comet
Inner planet
The planets closest to the sun; Mercury, Venus, Earth, and Mars
Jovian planets
the large, outer planets made of gas - Jupiter, Saturn, Uranus, & Neptune
Kuiper belt
the region of the solar system outside the orbit of Neptune that is occupied by small, icy, cometlike bodies
Meteor
the luminous phenomenon observed when a meteoroid enters Earth's atmosphere and burns up, popularly called a shooting star
Meteorite
The part of a large meteoroid that survives its trip through the atmosphere and strikes Earth's surface
Meteoroid
solid particles smaller than asteroids and comets that orbit the sun
Meteor shower
a brief period when the earth passes through a cluster of meteroids, causing more meteors than usual to be seen
Nebular hypothesis
a model for the origin of the solar system that assumes a rotating nebula of dust and gases that contracted to produce the Sun and planets
Oort cloud
(astronomy) a hypothetical huge collection of comets orbiting the sun far beyond the orbit of Pluto, A spherical region of comets that surrounds the solar system out to more than 1,000 times the distance from the sun
Outer planet
the 5 planets farthest from the sun - Jupiter, Saturn, Uranus, Neptune, and Pluto
Terrestrial planets
the name often given to the four inner planets: mercury, venus, earth, and Mars